Various steerable three-wheeled carts have been proposed for transporting bulky or heavy loads. Examples include those disclosed in U.S. Pat. Nos. 1,876,788 and 3,295,482. In both examples, the carts include a frame mounting a pair of non-steerable back wheels and a steerable front wheel assembly coupled directly to a pivoting handle that, when moved laterally, imparts steering movement to the front wheel for steering the cart. Although highly maneuverable, such carts can be difficult to handle on uneven terrain such as when traveling down or along an inclined surface.
U.S. Pat. No. 3,551,001 discloses a four-wheeled cart having a frame supported on four castered wheels. A handle is pivoted to the front of the frame and mounts a pair of braking members that engage the front castered wheels when the handle is pivoted downward. Although such engagement of the front wheels by the braking mechanism slows the cart, it inherently disables the castering movement of the front wheels and thus renders the cart nonsteerable.